Mobile audio devices such as mobile phones are getting smarter and are more and more equipped with “always-on” functionalities, which continuously sense the environment to perform anticipative actions such as device wake-up, voice keyword detection. Always-on functionalities have very low power requirements, which may be typically lower than 1 milliwatt (mW), and usually make use of dedicated sensors and low power hardware components implemented as integrated circuits in order to function independently from the main processor. This is particularly the case for wearable mobile audio devices such as active earbuds or watches. In case of voice activation, the main processor is only woken up by the voice activation system if a dedicated keyword has been recognized. In order to minimize power consumption, a multi-stage detection is usually applied.